Hr. vel . } . ( 1979), 135, 11 9

FACTORS AFFECTING THE FREQUENCY OF ISOLATING STREPTOCOCCUS AGALACTIAE FROM HERD MILK SUPPLIES AND THE CONTROL OF THE ORGANISM IN THE DAIRY HERD By]. K. L. PEARSON , D. A. POLLOCKANOD. O. GREER

Government oj Northern Ireland Department of Agriculture, Veterinary Research Laboratories Stormont, Belfast, Northern Ireland

SUMMARY

The prevalence of Str. agalactiae throughout the world is summarized in relation to the need for adequate monitoring systems which might be helpful to those who wish to initiate control systems. While some countries have made considerable progress towards eradicating the organism from dairy herds, others have appeared to make none at all. Fifty-one herds comprising 862 cows were studied in Northern Ireland, the incidence of Str. agalactiae being monitored by monthly culturing of the bulk milk supply for a full year. The frequency of isolations per month varied from 0 to 12 and was correlated with the percentage of infections and latent infections in cows and quarters using strict techniques and definitions. 3400 quarter milk samples were cultured, the overall number of cows infected being 27% and quarters II · 7%. The inclusion of Str. agalactiae 'isolates' increased these percentages to.33 and 16% respectively. On statistical analysis better correlations were obtained using infections alone than when isolations from quarter samples were included, the results being very highly signihcant (P

Factors affecting the frequency of isolating Streptococcus agalactiae from herd milk supplies and the control of the organism in the dairy herd.

Hr. vel . } . ( 1979), 135, 11 9 FACTORS AFFECTING THE FREQUENCY OF ISOLATING STREPTOCOCCUS AGALACTIAE FROM HERD MILK SUPPLIES AND THE CONTROL OF THE...
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